1. Field of the Invention
The present invention generally relates to a thin film transistor (TFT) array and a fabricating method thereof. More particularly, the present invention relates to a top-gate TFT array, an ESD protective device thereof, and methods for fabricating the same.
2. Description of Related Art
Electrostatic discharge is a phenomenon that electrostatic charge moves along the surface of a non-conductive material, which might damage circuit devices in an integrated circuit and other circuitry. For instance, when a human being is walking on a carpet, hundreds or even thousands of voltages of electrostatic potential might be detected under high relative humidity, whereas even tens of thousands of voltages might be detected under low relative humidity.
During a fabrication process of a liquid crystal display (LCD), relevant machinery platforms and technicians under operation can carry electrostatic charges, thus when these charge bearers contact the LCD panels, an electrostatic discharge event might take place, and the momentary discharge might harm the LCD devices and permanently disable the circuitry.
In order to avoid TFTs and circuitry damage caused by ESD, an ESD circuit is generally equipped on a LCD panel. Wherein, scan lines are connected to a common driving signal line, and the data lines are connected to a common data signal line. The common driving signal line and the common data signal line are connected to ground terminals. Therefore, when the amount of the accumulated static electricity is over a predetermined range, the accumulated static electricity can be dispelled through the ground terminals to avoid TFTs and circuitry damage caused by ESD.
In addition, when performing an electric test on the pixels of the LCD panel, a first voltage is applied to one of the scan lines to turn on the TFTs on the selected scan line. Then, a second voltage is applied to one of the data lines to thereby write data into a test pixel. However, since the scan lines and the data lines are electrically connected to common driving signal line and the common data signal line respectively, the first voltage is applied via the common driving signal line to the other scan lines, and the second voltage is applied via the common data signal line to the other data lines. Conversely, when a voltage is applied to the scan line to thereby read the data of the testing pixel from the data line, the voltage is applied via the common driving signal line to other scan lines, and it is impossible to derive a voltage peculiar to the pixel. Thus, it is impossible to detect a defective pixel.